B2C Commerce API 500 Internal Server Error InvalidScapiInternalTokenException Occurring With SCAPI Requests

The B2C Commerce API (SCAPI) endpoint getProducts returns the following 500 Internal Server Error with a stack trace:

 "com.demandware.wapi.exception.InvalidScapiInternalTokenException: Failed to validate SCAPI C2C JWT. Reason : Error while retrieving public key for service: scapi_shopper_products and kid:"

The B2C Commerce API goes by a few different names: Salesforce Commerce API, the acronym SCAPI, or just Commerce API.

The following is an example of the request and response:

Request:
curl —location —request GET ‘https://{shortCode}.api.commercecloud.salesforce.com/product/shopper-products/v1/organizations/{organizationId}/products/{productId}?siteId=SiteGenesis \
--header 'Authorization: Bearer {bearerToken}\ ''

Response:
{
"title": "Internal Server Error",
"type": "https://api.commercecloud.salesforce.com/documentation/error/v1/errors/internal-server-error",
"detail": "Internal Server Error"
}